This disclosure relates to a gas turbine engine, and more particularly to a composite airfoil.
An airfoil, such as a fan blade for a turbine engine, typically includes a main body formed from a strong and durable metal alloy. The metal alloy provides a desired degree of strength and durability under the operating conditions of the engine and resists damage from ingested foreign objects. To reduce weight and cost, the fan blade may include a composite cover. The composite cover may include one or more laminated layers. Generally, the composite cover is adhesively bonded to a main body of the airfoil. However, the main body has the tendency to yield at a different rate than the composite cover. Laminated structures are susceptible to delamination failure which can result in the liberation of plies and dramatic loss of structural capability.
Therefore, an adhesively bonded composite cover presents certain challenges. In particular, the composite cover has to maintain sufficient structure and integrity after a first strike event. Both the bond and the cover must be durable enough to meet the Federal Aviation Administration (FAA) bird strike requirements. Accordingly, a durable, lightweight, and easily bonded cover design is desirable.